The OLED (Organic Light-Emitting Diode) display has been widely applied in the filed of display technology. The basic structure of the OLED display comprises an anode, a luminescent layer and a cathode, wherein the luminescent layer is formed using the organic electroluminescent material.
The OLED generally realize color display by two ways: one is using a white organic light emitting material combined with a color filter to realize color display. Since part of the light is absorbed by the color filter, the display luminance is reduced by using such a method to realize color display.
The other is using a high fine metal mask plate (FMM) to plate the organic light emitting materials of different primary colors to form respective pixels. Whereas the area of the pixel formed by evaporating of the metal mask plate is related to the display resolution, the higher the resolution is, the density of the pixel is larger, the area of the pixel is smaller. Take the display screen of 5 inch full high definition (FHD) as an example, the display resolution is 1080×1920, then the pixel density on the substrate is approximately 440 PPI, for sub-pixels including three colors of red, green and blue, each sub-pixel is about 19.22 um×57.65 um.
However, in consideration of the factor that the luminous efficiency of blue is low generally, the area of the blue sub-pixel will be increased in a pixel, the areas of the red and green sub-pixels will be reduced. Limited by the FMM evaporating process, in the case that the area of the blue sub-pixel is larger than the area of the red and the green sub-pixels, the process difficulty of reducing the area of the red and the green sub-pixels further through the FMM process is significantly great, the cost is also very high, thus it would be impossible to reduce the area of the sub-pixel and increase the display resolution through the FMM evaporating process.